1. Technical Field
The present disclosure relates to a waterproof axial flow fan.
2. Related Art
An axial, flow fan has, for example, a rotary motor as a rotary driving device, an impeller mounted to a rotating shaft of the rotary motor and having a plurality of rotor blades, and a cylindrical casing forming an airflow together with the impeller.
In particular, in a waterproof axial flow fan, a stator of the rotary motor is coated with resin. Therefore, in the waterproof axial flow fan, the gap between a resin surface at the apex of stator and a rotary cover is narrow. Thus, the waterproof axial flow fan basically has such a structure that water does not easily reach a bearing.
JP-A-07-195933, for example, discloses a technique for preventing infiltration of water in the axial flow fan. According to the fan shape disclosed in this publication, there is provided a drip part covering the circumference of the rotating shaft. The drip part is provided with a flange-like drip ring for preventing the infiltration of water into the motor. A watertight cylinder is provided at the center of the impeller to cover the circumference of the rotating shaft and reach the vicinity of the motor. The tip of the watertight cylinder protrudes further than the drip ring toward the motor.
According to the fan shape disclosed in JP-A-07-195933, there are provided the flange-like drip ring and the watertight cylinder covering the circumference of the rotating shaft and reaching the vicinity of the motor. This suppresses the infiltration of water into the hearing of the motor.
Further, in the waterproof structure of the fan driving motor disclosed in JP-A-10-215537, the boss of the fan has a ring-like rib surrounding a bearing holding part. In the outer circumference of the rib, an inclined surface having a diameter that decreases toward die tip is formed.
According to the waterproof structure of the fan driving motor disclosed in JP-A-10-215537, a droplet dropped on the rib quickly falls down on the inclined surface. Therefore, a large amount of water does not remain on the rib. The water falls down onto the upper surface of the bearing holding part little by little and drops downward along the arc surface. This suppresses inflow of the water into the bearing part from the tip of the bearing holding part.